Problem: What do the following two equations represent? $4x-4y = -3$ $20x-20y = -4$
Explanation: Putting the first equation in $y = mx + b$ form gives: $4x-4y = -3$ $-4y = -4x-3$ $y = 1x + \dfrac{3}{4}$ Putting the second equation in $y = mx + b$ form gives: $20x-20y = -4$ $-20y = -20x-4$ $y = 1x + \dfrac{1}{5}$ The slopes are equal, and the y-intercepts are different, so the lines are parallel.